H lawson



Dec. 15, 1964 R. H. LAWSON ETAL 3,161,032

TENSION DEVICE FOR ELASTICYARN Filed Dec. 20, 1961 4 Sheets-Sheet l FIG. I

- I INVENTORS 1 ROBERT H. LAWSON JOHN B. LAWSON BY 62AM GL2 ATTORNEYS R. H. LAWSON ETAL 3,161,032

TENSION DEVICE FOR ELASTIC YARN Dec. 15, 1964 Filed Dec. 20, 1961 4 Sheets-Sheet 2 FINVENTORS H. LAWSON LAWSON ATTORNEYS 1964 R. H. LAWSON ETAL 3,161,032

TENSION DEVICE; FOR ELASTIC YARN Filed Dec. 20, 1961 4 Sheets-Sheet 3 INVENTORS ROBERT H LAWSON JOHN B. LAWSON ATTORNEYS Dec. 15, 1964 R. H. LAWSON ETAL 3,161,032

TENSION DEVICE FOR ELASTIC YARN Filed Dec. 20, 1961 4 Sheets-Sheet 4 INVENRME ROBERT H. LAWSON JOHN B LAWSON BYGDMQ'SGDMQ ATTORNEYS v1 in FIG. 1.

United States Patent O 3,161,032 TENSION DEVIOE FOR ELASTIC YARN Robert H. Lawson, Pawtuclret, and John B. Lawson, Barrington, RJL, assignors to Lawson Engineering (30., Pawtucket, Rl, a corporation of Rhode Island Filed Dec. 20, 1961, Ser. No. 160,854 9 Claims. (ill. 66-146) This invention relates to devices for tensioning bare elastic yarns as they are laid or knit into elastic fabrics.

It is common practice to use disc-type tensions for tensioning covered rubber yarns as they are laid or knit into elastic fabric, but such tensions are not entirely satisfactory when the elastic yarn, whether rubber or spandex, such as Lycra, Vyrene, etc., is bare. Bare elastic yarns, particularly bare spandex yarns, tend to adhere to polished metal and ceramic surfaces, in consequence of which they tend to adhere to disc-type tensions and make stretching of the yarn erratic. In addition, with a disc-type tension the starting tension is severe when compared with the running tension, which is a very undesirable operating condition because in the handling of bare elastic yarns slight variations in tension result in disproportionate changes in the amount of stretch. Accordingly, an important object of the present invention is to provide a tension device for bare elastic yarns which effectively eliminates erratic stretching and/ or disproportionate changes in the amount of stretch.

Another object is to provide such a tension device with yarn snubbing means controlled by an arm responsive to the amount of tension on the yarn, the movement of the arm in response to said tension being slight to eliminate oscillation of the arm due to inertia.

Another object is to provide such a tension device which normally is not sensitive to the amount of tension on the yarn as it leaves the spool.

Another object is to provide such a tension device which automatically relieves tension on the yarn when the yarn finger is taken out of action.

Another object is to provide such a tension device which permits feeding of the yarn immediately when the tension on the yarn, between the tension device and the machine, reaches a predetermined amount due to machine demand, and which terminates feeding of the yarn when the machine demand for yarn ceases, as due to needle selection or removal of the yarn.

Other objects of the invention will become apparent when the following description is read with reference to the accompanying drawings, in which:

FIG. 1 is a perspective View, showing the tension device mounted upon a knitting machine;

device; and

FIG 6 is a view looking in the'direction of the arrow Referring particularly to FIG. 1, the tension device, generally designated 10, constructed in accordance with the invention is mounted upon the crossbar 12 of a bobbin stand 14 associated with a knitting machine, gen

full fashion machines, V-bed machines and flat opposed 24 and 26. The frame 18 is provided with a pair of cars 28, and a pair of screws 30 extending through the ears 28 secure the frame 18 to the crossbar 12. Referring particularly to FIG. 5 a shoulder screw, generally designated 32, is provided with a slotted head 34 and a main body 36 terminating in a reduced diameter threaded portion 38. One end of a shaft 40 is projected into and afiixed to theportion 38 of the screw 32. The body 36 of the screw 32 is projected into an opening 42 in the side 24 of the frame 18 and is turnable therein. The free end portion of the shaft 40 is turnabiy received by an opening 44 in the side 26 of the frame. Fitted over the body 36 and disposed between the outer surface of side 24 of the frame and the head 34 of the screw 32 is a crimped washer 46. Mounted on the portion 38 of the screw 32 is a flat Washer 48. Disposed over the shaft 40 is a hollow cylindrical, generally designated 50, having a side 52 and a rim 54-. The side 52 is threaded onto the portion 38 of the screw 32. Formed on the outside of the rim 54 are circumferentially equally spaced axially extending grooves 56. Affixed to the side 52 of the casing 51) and disposed parallel to the axis thereof is a pin 5'8. Within the casing 50 is a coil spring 60. The outer end 62 of the spring is anchored to the pin 58, and the inner end 64 of the spring is anchored in a slot 66 formed in a reduced diameter portion 68 of a hub 7d.

Fitted over the hub portion 68 is one end portion of a control arm, generally designated 72. The arm is affixed to the hub '70 by means of screws 74. At the opposite end of the arm 72 is an opening 76 which receives a guide eye 78.

The periphery of the hub 70 is provided with a flat area 84) upon which is seated a snub bar 82. The bar is recessed, as at 84, to provide a pair of ears 86 which accommodate a pin 88 mounting a free turning roller 90. Seated upon the snub bar 82 is a bifurcated yarn guide 92. A screw 93 extends through an elongated opening 94 in the yarn guide 92 and an elongated opening 96 in the snub bar 82 and is threaded into the hub 70 to hold the snub bar and the yarn guide in position.

The hub 7t) is undercut, as at 98, to provide a recess 109 which accommodates a pin 102 for a purpose to appear.

A member 104 threaded into the back 22 of the frame 18 accommodates a spring-pressed plunger 106. The back 22 of the frame has an extension 108 with an opening 110 which receives a guide eye 112.

Atfixed to the side 26 of the frame 18 is an anvil 114 secured by screws 116. Extending fore and aft through the anvil is an opening 113. One edge of the anvil may be beveled to provide a forwardly and downwardly facing surface 120. The roller 90, throughout its entire length, engaged against the surface 120, preferably above the opening 118.

A shaft 122 has opposite end portions received by openings 123 in the sides 24 and 26 of the frame 18. Each end of the shaft is fitted with a cutter pin 124. Mounted on the shaft is a lever 126 provided with an upright arm 128 and a horizontally extending arm 130.

Also mounted upon the shaft is a lever 132 provided with a lateral extension 13 2-. interposed between the levers 126 and 132 is a flat washer 136. A tension coil spring 138 has one end 146 anchored to the lever 132 and the opposite end 142 anchored to the lever 126. The end 14-2 is selectively engageable in a series of notches 144 in the arm 128 for a purpose presently to be explained. A tension coil spring 146 has a lower end portion anchored to the lever 132 and an upper end portion 150 anchored to a screw 152 extending through the back 22 of the frame 18.

Aflixed to the back 22 of the frame 18 is a stop plate 154 for lever 132 secured by screw 152 and a screw 156. Referring particularly to FIGS. 3 and 6, a flexible wire cable or Bowden wire 158 is connected by an element 160 to the extension 134 of the lever 132. The wire extends through a cable 162, one end of which is attached by fitting 164- to the bottom 20 of the frame 18 and the opposite end of which is attached by a clamp 166 to a stationary bracket 168 on the back of the knitting machine. The free end of the Bowden wire passes freely through a stud 170 and terminates in a tip 172. The stud 170 is carried by an arm 174 which is pivoted, as at 176, and which is one of a series of levers controlled by the usual cams and ratchets for operating yarn fingers. The opposite end of the arm 174 controls an elastic yarn finger 178. Conventional mechanism for controlling the arm 174 and the neighboring arms that control the yarn fingers is generally designated 18%.

Yarn from a package thereof (not shown) extends upwardly freely and then forwardly through the guide eye 112. From the guide eye 112 the yarn extends forwardly through the opening 118 in the anvil 114, between anvil surface 120 and roller 90, then between the furcations of the guide 92 and thence along the control arm 72 to and through the guide eye 78. Then it extends downwardly to a standard Wesco drop wire stop motion, generally designated 182. From the stop motion the yarn extends through the finger 17S and into the fabric.

The yarn, designated 184, is drawn by the needles from the yarn package as the yarn is laid or knit into the fabric. This places tension on the yarn between the fabric being knit and arm 72. The tension on the yarn tends to move the end of the arm 72 downwardly against the influence of the clock type spring 6%. When the load on the arm 72, due to the tension on the yarn, is such as to balance out the influence of the spring 60, the end of the arm 72 tends to move downwardly, urging roller 90 slightly away from the surface 120 of the anvil 114. Thereupon the yarn, snubbed by the roller 90 against the surface 120 of the anvil 114, flows between said anvil and roller 90. Normally, no perceptible movement of the arm 72 occurs. So long as the tension on the yarn is above a predetermined amount, yarn will flow between the anvil and the roller. When the tension on the yarn drops below the redetermined amount, because, for example, the yarn is no longer being demanded by the needles, or due to selection of the needles, the roller immediately clamps the yarn against the anvil and terminates flow thereof.

Pull on the elastic yarn between the yarn package and roller 90 does not affect the end result, i.e., the tension on the elastic yarn between the roller 90 and the needles, except when said pull induces a tension which exceeds that desired. The elastic yarn leading from guide eye 78 to the machine acts as a sprin tending to balance the influence of spring 60, and when the two forces do balance, yarn flows smoothly. Rotation of roller 99 prevents buildup of twist in the yarn as it is drawn over the end of the yarn package.

When finger 178 is taken out of action by operation of mechanism 130, the arm 174 swings to the right, as viewed in FIG. 6, about pivot 176, whereupon stud 170 engages tip 172 and the Bowden wire 158 is pulled to the right. Thus the levers 132 and 126 are pivoted counterclockwise, as viewed in FIG. 3, against the influence of spring 146, and arm 128 engages with pin 102, tending to urge it clockwise about shaft 40, against the influence of spring 60. As a consequence, roller 90 is urged away from the surface 120 of the anvil 114-, relieving, i.e. reducing, the tension on the elastic yarn as the yarn finger 178 goes out of action and guides its yarn into the usual clamp and cutter, thus permitting it to be more readily clamped.

The extent to which spring 60 is counteracted, and hence the extent to which tension on the elastic yarn is reduced by diminishing the pressure between roller and anvil 114, depends on which notch 144 the end 142 of spring 138 is selectively engaged. This counteraction against spring 60 reduces the force on arm 72, and as the tension on the withdrawn elastic yarn drops below this reduced force on arm 72, roller 90 and anvil 114 act to clamp the yarn.

When it is desired to knit the elastic yarn in one or more courses of the fabric and then lay it in the fabric without knitting, the Bowden wire 158 is fastened to a lever (not shown) controlled by the main drum of the knitting machine so that tension on the elastic yarn is low during knitting and then high during inlaying.

It will be noted that levers 132 and 126 are capable of movement relative to each other against the influence of spring 135.

The influence of clock type spring 60 may be varied as desired by turning casing 59 and screw 32 as a unit about the axis thereof to wind spring 66) more or less tightly. The casing is held in a selected position by plunger 166 which engages in a selected groove 56. The force exerted by arm 128 upon the pin 102 may be varied as desired by connecting the end 142 of spring 138 at a selected notch 144, thus varying the degree to which spring 60 is counteracted by movement of arm 128.

It should be noted that whether or not yarn flows between the anvil 114 and roller 90 depends upon the magnitude of the tension exerted on the yarn between the guide eye 78 and the needles. Movement of the arm 72 is very slight, so that movement due to inertia is negligible, if not eliminated altogether.

It should also be noted that the arm 72 is extremely sensitive and responds immediately when the flow of yarn should be increased to relieve excessive tension on the yarn and responds immediately to terminate the flow of yarn when tension on the yarn has decreased below the desired amount, as due to removal of the yarn from feeding position.

It will be understood, of course, that the present invention, as described and shown, is susceptible to various changes and modifications which may be made without any departure from the general principles or real spirit of the invention. Accordingly, it is intended to claim the present invention broadly, as well as specifically, as indicated in the appended claims.

Having thus described our invention, we claim as follows:

1. In combination with knitting mechanism including a feed finger for elastic yarn and means for controlling said feed finger, means for feeding an elastic yarn under tension to said finger comprising a member having an axis about which the same may be rocked, yarn snubbing means controlled by said member, means yieldably biasing said member in yarn snubbing direction, means for counteracting the influence of said biasing means in response to movement of said feed finger control means to take said finger out of action, and means on said memher for guiding said yarn, the distance between said axis and yarn guide means being substantially greater than that between said axis and yarn snubbing means.

2. In combination with knitting mechanism including a feed finger for elastic yarn and means for controlling said feed finger, means for feeding an elastic yarn under tension to said finger comprising a member having an axis about which the same may be rocked, yarn snubbing means controlled by said member, means yieldably biasing said member in yarn snubbing direction, means operable for counteracting the influence of said biasing means, means yieldably biasing said counteracting means to inoperative position, means for actuating said counteracting means against the influence of its biasing means in response to movement of said feed finger control means to take said finger out of action, and means on said memher for guiding said yarn, the distance between said axis v and yarn guide means being substantially greater than that between said axis and yarn snubbing means.

3. In combination with knitting mechanism including a feed finger for elastic yarn and means for controlling said feed finger, means for feeding an elastic yarn under tension to said finger comprising a member having an axis about which the same may be rocked, yarn snubbing means controlled by said member, means yieldably biasing said member in yarn snubbing direction, a pair of levers mounted for pivotal movement independently of each other, yieldably secured against such movement and operable for counteracting the influence of said biasing means, means yieldably biasing said levers to inoperative position, and means for actuating said levers against the influence of the last mentioned biasing means in response to movement of said feed finger control means to take said finger out of action, and means on said member for guiding said yarn, the distance between said axis and yarn guide means being substantially greater than that between said axis and yarn snubbing means.

4. In combination with knitting mechanism including a feed finger for elastic yarn and means for controlling said feed finger, means for feeding an elastic yarn under tension to said finger comprising a member having an axis about which the same may be rocked, yarn snubbing means controlled by said member, means yieldably biasing said member in yarn snubbing direction, a pair of levers mounted for pivotal movement independently of each other, means yieldably tying said levers together with a predetermined selectively variable force, said levers being operable for counteracting the influence of said biasing means, means yieldably biasing said levers to inoperative position, and means for actuating said levers against the influence of the last mentioned biasing means in response to movement or said feed finger control means to take said finger out of action, and means on said member for guiding said yarn, the distance between said axis and yarn guide means being substantially greater than that between said axis and yarn snubbing means.

5. In combination with knitting mechanism including a feed finger for elastic yarn, and means for controlling said feed finger including a lever, and a drum operable for controlling said lever, means for feeding an elastic yarn under tension to said finger comprising a member having an axis about which the same may be rocked, yarn snubbing means controlled by said member, means yieldably biasing said member in yarn snubbing direction, means for counteracting t-he influence of said biasing means in response to movement of said lever to modify the tension onthe elastic yarn as the mode of using it changes, and means on said member for guiding said yarn, the distance between said axis and yarn guide means being substantially greater than that between said axis and yarn snubbing means.

6. In combination with knitting mechanism including a feed finger for elastic yarn and control means for moving said finger into and out of feeding position, a tension device for said elastic yarn comprising an arm mounted for rocking movement about a pivotal axis, yarn snubbing means controlled by said arm, means yieldingly biasing said arm in yarn snubbing direction and means operative to counteract the influence of said biasing means in response to action by said feed finger control means moving said finger out of feeding position.

7. The invention of claim 6 further including an anvil against which the yarn snubbing means is biased to apply tension to the yarn as it is fed, means for directing passage of the yarn between the anvil and the yarn snubbing means and selective control means for regulating the force by which the snubbing member is biased against the anvil.

8. A tension device for selectively applying tension to elastic yarn comprising an arm mounted for rocking movement about a pivotal axis, a tree turning roll connected to said arm for rocking movement therewith, an anvil disposed to cooperate with said roll to apply tension to the yarn, a yarn passage through said anvil, means yieldably biasing said arm in a direction for squeezing yarn emerging from said passage between said roll and anvil to thereby tension the yarn and selective control means for regulating the extent to which the yarn is squeezed between said roll and anvil.

9. The invention, of claim 6 further including means for selectively varying the degree to which the influence of the biasing means is counteracted.

References (lifted by the Examiner UNITED STATES PATENTS 2,123,174 7/38 Lindley 66-132 2,168,224 8/39 Lawson et al. 66-l34 2,252,637 8/41 Lawson 66-146 X 2,554,493 5/51 Heizer 242-15O 2,630,281 3/53. Kent 242154 2,767,567 10/56 Jenard et a1 66146 X 2,896,435 7/59 Berg 66146 3,099,143 7/63 Sinclair 66-432 RUSSELL C. MADER, Primary Examiner. 

6. IN COMBINATION WITH KNITTING MECHANISM INCLUDING A FEED FINGER FOR ELASTIC YARN AND CONTROL MEANS FOR MOVING SAID FINGER INTO AND OUT OF FEEDING POSITION, A TENSION DEVICE FOR SAID ELASTIC YARN COMPRISING AN ARM MOUNTED FOR ROCKING MOVEMENT ABOUT A PIVOTAL AXIS, YARN SNUBBING MEANS CONTROLLED BY SAID ARM, MEANS YIELDINGLY BIASING 